HIGHLIGHTSNew polymerisation methods feature in this issue with a number of items concerning ATRP, also RAMP and nitroxide mediated radical polymerisation. Notable is the industrial interest with a number of patented process variations. Three items have been included in the applications section on radiation curing, showing the interest in applying radiation cure to all coatings applications, with clear coats, electrocoating and powder coats each being featured. Finally on the theoretical front, modelling advances are noted with both free radical and condensation polymerisation modelling which extends into the gel region, the latter with two papers from Harmon Rays group in Madison, Wisconsin.

NEWS Those whose interest is in synthetic chemistry may note that Organic Synthesesare now available in fully searchable form at www.orgsyn.org. A wide variety of search possibilities are presented including use of a ChemDraw plug-in to search structures. Organic Syntheses presents detailed experimental methods in a standard format for the synthesis of organic compounds, in some 77 annual volumes and 9 collective volumes published by John Wiley. The contents are selected and independently checked synthesis procedures for a wide variety of materials.

NOTES This publication regularly features both book reviews and notices of meetings, conferences etc. Books may be submitted for review to the editor c/o PRA, UK. Notices of meetings for inclusion may be sent to the editor, either to the PRA at the address given, or to his personal e-mail address, given below. Assistance in obtaining copies of original articles and publications featured in this bulletin is available from the PRA library. The abbreviations and naming conventions that the editor endeavours to use follow as closely as is practical to those recently published. The chapter is Polymer Nomenclature by L H Sperling et al in Craver, C D & Carraher, C E, (eds), Applied Polymer Science 21st Century, Elsevier Science, 2000, ISBN 0 008 0434177, pp.49-54. A glossary is included of common abbreviations, and the most common such as BADGE, PU, PVC, St are likely to be used without expansion in the text. However it is still the intention to use the full name/expression of any that are likely to be less familiar in the body of the publication, even if they appear in the glossary.

John Bentley, Editor E-mail john_bentley@btinternet.com

1.

THEORETICAL AND GENERAL

Adhesives A rapid-curing 2-pack adhesive composition is claimed, giving high initial bond strength, good penetration properties and high post-cure bond strength and water resistance. An intended use is for laminates where current products may degrade with time or be thermally unstable. The composition comprises as its first component an aqueous solution or dispersion of a water-soluble polymer with carboxyl and hydroxyl groups and aqueous polymer with primary amino and secondary amino groups, and as second component, a water-soluble aldehyde compound. The aqueous polymer reacts immediately with the aldehyde compound, to give a low-MW gel with good elasticity and viscosity; a second gelation reaction occurs subsequently between the water-soluble polymer and the aldehyde compound. In the first example, aqueous solution of carboxylated polyvinyl alcohol is mixed with polyethylene imine to give the first component. This is mixed with an aqueous solution of glyoxal as the second component. A table shows initial strength after a period of up to 5 minutes with the joint under compression, after which strength increases further up to 24 hours. An alternative to carboxylated polyvinyl alcohol is carboxylated methyl cellulose. The adhesive may contain other components as specified. [301] Wan, J, Kamikaseda, T et al, (National Starch and Chemical Investment Holding Corporation), PCT WO 99/58622. Publication Date 18.11.1999. Filing Date 12.05.1999. Also European Patent 1 040 174 A. Modelling The modelling of condensation polymerisation with multiple monomers has been achieved using a linkage moment approach, applied first of all to linear polymers, and then (second publication), extended to nonlinear polymers. A general copolycondensation model has been presented which can include any number of monomers of differing reactivities. The first paper gives fullest detail of the model developed for mono and bifunctional monomers. The effects of forward and reverse polycondensation, alcoholysis and acidolysis as well as direct linkage exchange are all considered. The use of the approach is validated for the situation where a polyarylate (bisphenol A/isophthalate/terephthalate) is melt blended with p(butylene terephthalate) to produce a copolymer whose average sequence length may be controlled by limiting the extent of reaction. This model is then extended with the inclusion of multifunctional monomers, including use of the Miller/Macosko approach to gelation and beyond, including sol/gel properties. It is claimed that the microstructure of a wide variety of systems can be described as for example those where the copolymer has a blocky microstructure caused by interchange reactions between multiple components. [302] Beers, K J & Ray, W H, J. Appl. Polym. Sci., 10 Jan.2001, vol.79 (2), pp246-265, pp266-274.

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The post gelation period has been studied in free radical crosslinking polymerisation, examining the effect of inactive gel radicals on gel growth. A divinyl/monovinyl monomer system is considered, with the author first reviewing previous work, notably the McMaster work of Tobita and of Zhu. The gel model here takes into account the nonrandom termination of radicals, the model assuming that the termination reaction of radical centres bound to the growing gel molecule react with each other by a propagation diffusion mechanism. This is developed with rate and moment equations, with then the fraction of radicals and polymers in the sol taken into account. Calculation results demonstrate that the existence of trapped radicals significantly affects the growth rate of the gel molecule. Differences in predictions compared to not considering trapped radicals are considered relating to crosslinker concentration, and relative vinyl group reactivity on crosslinker and polymer. Predictions are compared with results for the system of acrylamide crosslinked with N,Nmethylenebis(acrylamide). [303] Okay, O, Macromol. Theory Simul., 2000, vol.9(6), pp.354-361. Network Studies Polytetrahydrofuran amphiphilic networks have been synthesised and characterised. Polytetrahydrofuran acrylate was prepared by the direct esterification of ",T-dihydroxy poly(THF) of MW 2000 with acrylic acid. Polyacrylamide-polytetrahydrofuran networks were prepared in THF using benzoyl peroxide as catalyst; the network structures as drawn are of ladder form and described as novel. Acrylamide levels varied between 20 and 70%, the remainder being pTHF acrylate. Characterisation was by FTIR and by swelling, the latter showing the networks to swell in both hydrophilic and hydrophobic solvents showing them to be amphiphilic with both hydrophobic and hydrophilic segments. Microphase structure was examined, DSC supporting the presence of a microphase separated structure. A typical SEM micrograph is included. [304] Guan, Y et al, J. Polym. Sci., Polym. Chem., 15 Oct.2000, vol.38 (20), pp3812-3820. Commercial poly(vinyl alcohol) (pVAlc) has been crosslinked with HDI in solution and the mechanical and thermal properties studied. The pVAlc was of MW 22,000 and 85% hydrolysed. The crosslinking was carried out in DMSO/DMF solution, the compatibilised mixture being cast on plates to obtain films. The reaction was uncatalysed, and crosslinking levels were up to 74% were achieved. From DMTA examination, thermal and mechanical properties were seen to show an initial decrease with crosslinking due to a reduction in the crystallinity of the system. Properties then rose abruptly at around 20% crosslinking, not then rising significantly to the maximum level of crosslinking. Explanation covers a number of factors. Firstly, the existing network due to hydrogen bonding is diminished and is replaced by a chemical network. Secondly the crosslinks introduced by the HDI are flexible. Data includes storage modulus, loss tangent and loss modulus curves. The evolution of properties with crosslinking % change are recorded in a series of graphs. [305] Krumova, M et al, Polymer, 2000, vol.41(26), pp.9265-9272. Pol(isobutylene) gels have been prepared from butyl rubber in toluene solution, and the swelling behaviour studied. Crosslinking was carried out using sulphur monochloride added to solutions with stirring, the gel then recovered in bead form after addition of toluene swollen gel to water. Variables were the rubber solution concentration in toluene and the crosslinker concentration used. Gels were swollen in a range of solvent mixtures. Swelling capacity in toluene increased with decreasingPage 2

THEORETICAL AND GENERAL

crosslinker and decreasing initial rubber concentration in toluene. The solubility parameter of gels was found to be 16.8 MPa 0.5 similar to that for bulk crosslinked gels. It was found that in toluene/methanol, that pIB gels with 4% crosslinker exhibited an abrupt deswelling when the toluene content of the mixture was decreased from 97 to 90%. It was shown by using the theory of equilibrium swelling that the gel passes through critical conditions as the quality of the solvent becomes poorer. The data from all swelling experiments is shown in a range of graphs. [306] Okay, O et al, Macromolecules, 2000, vol.33(13), pp.4822-4827. New Polymerisation Methods : ATRP The atom transfer radical polymerisation (ATRP) of 2-hydroxyethyl methacrylate (HEMA) has been reported under what the authors call mild and industrially attractive conditions. Yields of 95% poly HEMA were obtained in water/methanol at 20EC using Cu(I) Br catalyst and bipyridyl, with oligo(ethylene glycol) based initiator. The Cu(II) catalyst residues were subsequently removed with silica treatment. Mn values by NMR were in the range 4000 to 10,000 and close to those theoretically predicted, with Mw/Mn at best of 1.09. In the fastest example shown, conversion was substantially complete in 70 minutes. The authors also report the preparation of comb shaped graft copolymer preparation with methoxy PEGMA (EO45). Diblock copolymers were also prepared with blocks of PEGMA and HEMA. The second paper noted was the previous most successful ATRP preparation of pHEMA, achieving 72% conversion at 70EC with Mw/Mn 1.3, or 87% conversion at 50EC with Mw/Mn > 1.5. In this case, MEK/propanol or less successfully DMF were used as solvents. [307] Robinson, K L et al, ACS PMSE, Apr. 2001, vol.84, pp.58-59. Beers, K.L. et al, Macromol., 7 Sept.1999, vol.32 (18), pp5772-5776. ABC type copolymers are claimed, useful for powder coatings, the end blocks having crosslinkable functional groups, the mid block being free of reactive functional groups. They are obtained by controlled radical polymerisation (ATRP) in the presence of halogen-containing initiator and a metal complex (Cu, Fe, Ru or Ni based) or compound. In examples, 2,2'-bipyridine, CuCl and dichloroacetic methyl or t-butyl ester have monomers sequentially added. In one example these are MMA/tBA, MMA and then MMA/tBA, this polymer then being heated to 200EC to decompose the tBu esters finally giving a COOH functional acrylate copolymer. In another example, the sequence is first addition of MMA followed by addition of tBA. Again the polymer is heated to 200EC to decompose the tBu esters. The first of the polymers just described was also transformed into OH functional copolymer by treatment with propylene oxide. In examples, these copolymers are used in powder coating compositions with epoxidised oil, TGIC, glycoluril resin or blocked isocyanate as appropriate as crosslinker. Powder coating compositions are claimed, and also the use of binder in solvent borne and waterborne coating compositions. The cured coatings have good mechanical properties and improved chemical resistance. [308] Udding-Louwrier, S et al, (DSM NV). European Patent 0 962 473 A. Publication Date 08.12.1999. Filing Date 04.06.1998. An atom transfer radical polymerisation process (ATRP) giving increased polymerisation rate and monomer conversion is claimed, using a reduced proportion of transition metal compound catalyst. The process comprises the polymerisation of vinyl monomers by contacting, in liquid medium, firstPage 3

CURING TYPES

the compound containing the transition metal compound and secondly a compound capable of radically transferring the atom or group to the first compound and also vinyl monomer, while irradiating with visible light. CuCl and 2,2'-bipyridyl are used with 2,2'dichloroacetophenone and MMA monomer. Polymerisation was in a glass vessel at 80EC under irradiation with a sunlamp for 16 hours. It was shown comparing this with carrying out the same experiments in the dark, that as described, much faster conversion rates and narrower MW distributions were obtained. [309] Guan, Z & Smart, B E, (DuPont). PCT WO 99/10387. Publication Date 04.03.1999. Filing Date 25.08.1998. Also European Patent 1 007 573 A.2. CURING TYPES

2. CURING TYPES

Acrylate Functionality Acrylate functional telechelic polylactic acid has been synthesised by transesterification. A one step reaction gave product with Mn from 700 to 10,000, with transesterification carried out with a Lewis acid titanium catalyst, a high MW polylactic acid (pLA) and a diacrylate. In the example given, pLA of Mn 128,900 in dry toluene was reacted with either EGDMA or tetraethylene glycol diacrylate with titanium isopropoxide at 115EC. MW is determined by the amount of difunctional acrylate added. Product was characterised by GPC, NMR and MALDI- TOF MS. This latter showed the presence of a series of oligomers. Tgs of oligomers (unreacted) were from -35 to -5EC. Product was crosslinked by adding benzoyl peroxide and heating at 100EC, when the crosslinked product Tg was 40EC. Suggested application is for biodegradable material, it being shown that crosslinked material degrades progressively on storage by hydrolysis. [310] Coullerez, G et al, J. Mater. Sci.: Mater. Med., 2000, vol.11(8), pp.505-510. The preparation of (meth)acrylic acid esters of hydroxy-functional siloxanes or polyoxyalkylenemodified siloxanes is claimed by a process where these are obtained by the enzyme-catalysed (trans)esterification of siloxanes and an alkyl (meth)acrylate. They may be obtained using hydrolase, that is lipase, esterase or protease, especially in an immobilised form, preferably at 40-70EC. In the text a number of siloxane structures are drawn, many being that siloxanes have first a propylene oxide chain portion attached, and then an ethylene oxide portion. The terminal group may be hydroxy or methoxy. In the one example, a siloxane with attached [PrO]3 [EO]8 OH is reacted with butyl acrylate at 70E in the presence of Enzyms Novozym 435. Butanol is removed under vacuum, and after 8 hours the unreacted butyl acrylate. 65% of the OH groups were acrylated. The products are useful in dispersions, radiation-curable compositions, especially clearcoats, and radical polymerisation processes. Uses are claimed (in German). [311] Gruning, B et al, (Goldschmidt AG), European Patent 0 999 230 A. Publication Date 10.05.2000. Filing Date 21.10.1999. Allylic Functionality Novel water soluble cationic macromonomers of (dimethylamino)ethyl methacrylate (DMAEM) with terminal diallylmethyl or allylmethylphenyl ammonium groups have been made by living anionicPage 4

CURING TYPES

polymerisation. Initiators lithium diallylamide and lithium allylphenylamide were prepared first by reacting the N-substituted allylamines with butyl lithium, as is described. Polymerisation of DMAEM was carried out in THF in the presence of LiCl at -78EC. Polymerisation was terminated by the addition of MeOH and after separation was quaternised with methyl iodide. The allylphenylamide was the most efficient. The efficiency of the diallylamide could be improved by capping with dimethylacrylamide or t-butyl methacrylate, these having an initiator efficiency better than 0.9 giving polymers with predicted MW and nearly monodisperse. A table shows that materials with Mn from 4700 to 23,300 were produced at high conversions. The products were found readily copolymerisable with other vinyl monomers. Discussion and characterisation details are included. [312] Shen, Y et al, Macromol., 16 Jan.2001, vol.34 (2), pp144-150. Amino Functionality Soluble polymers have been prepared with controlled levels of secondary and tertiary amine functional (aminomethyl) groups, by reacting some or all of the double bonds of an olefin containing polymer. A two step process of hydroformylation and reductive amination was used. Examples are fully described, with butadienes of Mn 4500 and 8000. The reaction scheme is shown so that reaction with 1,4 units in the polybutadiene first gives aldehyde groups and then pendant i-propyl or n-butyl secondary amines. An autoclave is used for the first step reaction with H2/CO. Ru3(CO)12 was the catalyst for the second stage. A sequence is also shown for adding both secondary and tertiary amine groups to similar polymer. [313] McGrath, M P et al, ACS Polym. Preprints, Aug.2000, vol.41 (2), pp1513-1514. Anhydride/Enamine Stable one-pack compositions with high latency are claimed, which cure quickly on exposure to moisture or heat. These comprise an anhydride group containing oligomer or polymer such as maleic anhydride/butadiene copolymer and an enamino ester curing agent. (Bis)enamine curing agents are obtained by reacting diamines with acetoacetates, as described. A typical example is that pictured below.

This is prepared by the dropwise addition of ethyl acetoacetate (EAA) to 1,3-diamino-4methylcyclohexane. A number of other examples are similarly made by the addition of EAA to other diamines as described. These are used with polyanhydride prepared by the free radical reaction of polybutadiene with maleic anhydride. Property development as the mixtures moisture cure is described. Preparation of moisture-curing composition is claimed. [314] Fischer, W & Wegmann, A, (Ciba Specialty Chemicals Holding Inc). US Patent 6,107,451. Publication Date 06.05.1999. Filing Date 13.10.1998. Also European Patent 1 025 154 A.

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CURING TYPES

Aziridines Flame retardation improvement of aqueous-based polyurethane has been achieved by the use of aziridinyl phosphazene curing system. The 2,2,4,4,6,6-hexakis(1-aziridinyl)cyclotri-phosphaza1,3,5-triene (NPAZ) (illustrated) was synthesised from hexachlorocyclo-triphosphazene and aziridine as is described.

Aqueous polyurethane dispersion (PUD) was prepared from polypropylene glycol, DMPA and IPDI, this prepolymer then being mixed with triethylamine, having a final solids of 30% in water. Various levels of NPAZ were added to the PUD, film being cast and cured at room temperature and then 50EC. This treatment improved the properties over those of the untreated PUD films. A range of physical and mechanical properties were tested and results are included. Gel content, water uptake, ethanol swelling, TGA, TGA-interfaced FTIR and DMTA were employed. Thermal stability and flame inhibition properties were evaluated, it being demonstrated that NPAZ was serving a dual function as crosslinker and a reactive flame retardant. [315] Huang, W.-K. et al, J. Appl. Polym. Sci., 24 Jan.2001, vol.79 (4), pp662-673. Bicycloesters High build coatings compositions are claimed containing compounds with bicyclo orthoester groups capable of reacting with a second compound containing groups reactive with OH groups such as isocyanate, epoxy, acetal, carboxyl or anhydride, or which contain amino resin. The bicyclo orthoester groups hydrolyse with water or atmospheric moisture without release of volatiles and are latent OH groups. The preparation process for making the bicyclo orthoester compounds is via a corresponding oxetane compound. In the first example, the compound 4-ethyl-1(ethoxycarbonylmethyl)-2,6,7-trioxabicyclo [2.2.2] octane pictured below was prepared by the reaction of diethyl malonate and 3-ethyl-3-hydroxymethyl oxetane in the presence of dibutyl tin oxide.

This was used directly in formulations. In other examples, the simpler 4-methylol-1-ethyl bicyclo compound was prepared, and further reacted along with a hydroxy acetal material or triethoxy-3aminopropyl silane with HDI triisocyanate (biuret or isocyanurate). Coating compositions are then prepared with HDI triisocyanurate and catalysts showing pot stability with touch dry times of a few hours, developing good MEK rub resistance indicating cure. Preparation is claimed.Page 6

Carbonates A reactivity comparison of the reaction of five- and six- membered cyclic carbonates with amines has been published as a basic evaluation of use of this route for the synthesis of poly(hydroxyurethane). This reaction is useful for crosslinking and for novel polymer synthesis. 5-(2-Propenyl)-1,3,-dioxan2-one and 4-(3-butenyl)-1,3-dioxolan-2-one (illustrated) were synthesised.

The first was made by reaction of 2-allylpropane-1,3-diol with 2,3-dimethyl-1-phenyl-5-pyrazolone and triphosgene. The second was synthesised by treatment of 1,2-epoxy-5-hexene with carbon dioxide. Reactions with hexylamine and benzylamine were carried out in N,N-dimethylacetamide at 30, 50 and 70EC. The six membered carbonate was seen to react quantitatively with hexylamine at 30EC over 24 hours while the five membered carbonate went to 34% conversion. Rate constants and activation energies were determined. Full NMR and preparative data are included. [317] Tomita, H et al, J. Polym. Sci., Polym. Chem., 1 Jan.2001, vol.39 (1), pp162-168. Polyfunctional polycyclocarbonate oligomers are claimed, which are prepared by reacting oligocyclocarbonates having terminal epoxy groups with primary aromatic diamines. These are useful for curing with primary aliphatic diamines and for preparing adducts for curing epoxy resins for coatings, adhesives and sealants with high chemical resistance. These have the structure as shown below.

In examples, a number of epoxy-cyclocarbonates (with one epoxy group and one cyclic carbonate group) are used, these being prepared by reaction of epoxy oligomer and carbon dioxide as described separately (Israel Patent 122763). The aromatic diamine coreactants are for example m-phenylene diamine, 4,4'-diaminodiphenylmethane and 4,4'-diamino-diphenyloxide. After this reaction, primary amines such as N,N-bis(3-aminopropyl) methylamine are added. These oligomers are mixed with epoxy resins for curing. [318] Figovsky, O et al, (Polymate Ltd & Chemonol Ltd). European Patent 1 020 457 A. Publication Date 1907.2000. Filing Date 14.01.1999.

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CURING TYPES

Epoxides : Anhydride Curing The effect of side alkenyl chain length of the hardener have been studied for an anhydride-epoxy cured system, with particular respect to tensile and impact properties. Three different alkenyl succinic anhydrides were synthesised by the ene reaction, where maleic anhydride was reacted in an autoclave with 1-octene, 1-dodecene or 1-hexadecene in the presence of phenothiazine. Products were 2-octenyl, 2-dodecynyl and 2-hexadecenyl succinic anhydrides respectively. These were reacted with BADGE type liquid epoxy with triphenyl phosphine catalyst at 80EC, post cured for 2 hours at 80EC and 24 hours at 150EC. Contact angles were measured so that surface free energies could be determined. Increasing side chain lengths resulted in decreasing surface free energy. Decreasing Tg and tensile strengths also resulted. Impact properties however improved, related to an increasing London dispersive component of surface free energy. Fracture surface photographs are included. [319] Park, S-J & Lee, S-G, J. Coll. & Interface Sci., 1 Aug.2000, vol.228 (1), pp90-94. Epoxides : Amine Curing The curing and the decomposition kinetics for the system BADGE/di(4-aminobenzanilide) (ABAE) has been studied. This latter was prepared by the reaction of di(4-aminophenyl) ether and 4nitrobenzoyl chloride as is described. The product is pictured below.

BADGE and ABAE were reacted at 170EC to ensure completeness, and the Tg of the product as measured by DSC was 162.4EC. DSC scans at different rates are shown. The structure was confirmed by FTIR, NMR and elemental analysis. Curing kinetics and decomposition kinetics were elucidated by the Ozawa and Flynn-Wall equations respectively. The onset decomposition temperature (ODT) was found to be 346EC. [320] Hwang, S-H & Le, G-S, Europ. Polym. J., 2000, vol.36(10), pp.2305-2308. The mechanism for the curing reaction of model epoxy compounds with monuron has been explored. Monuron is p-chlorophenyl-N,N-dimethylurea and can be regarded as an isocyanate blocked amine. p-Tolylglycidyl ether as the model monoepoxide was synthesised from p-cresol and epichlorohydrin as is described. Possible intermediates were also synthesised. Thermo FTIR, DSC and liquid-solid chromatography were used to investigate the reaction of the monoepoxy with dicyandiamide and possible reaction products and reaction schemes are drawn out. It was found that the latent hardener monuron not only accelerates curing of epoxy with dicyandiamide but can also be used as a curing agent itself. Cure with monuron starts well below the thermal decomposition temperature. The reaction with epoxy liberates isocyanate which consecutively reacts with the aminoalcohol there as an intermediate or it reacts with oligomers resulting from its reaction with further glyclidyl ethers. Urethanes formed do not cyclise directly under elimination of dimethylamine but react with a further molecule of glycidyl ether to form 2-oxazolidone. This releases aminoalcohol or relating oligomer. Polymerisation proceeds as the favoured reaction, due to the catalytic effect of the basicPage 8

CURING TYPES

dimethylamino group of the amino-alcohol. [321] Brockmann, H et al, Int. J. Adhesion & Adhesives, 2000, vol.20(4), pp.333-340. Epoxy resin curing agents, giving cured coatings with low blush and low exudate and good surface appearance are claimed, used for fast drying systems. These are amine-terminated polyamidoamine resins obtained by reacting fatty monocarboxylic acid (tall oil or soya fatty acid), aromatic monocarboxylic acid (benzoic acid), aromatic dicarboxylic acid (isophthalic or terephthalic acid) and polyethylene amine in specified proportions. In examples, amines used are N-aminoethylpiperazine and triethylenetetramine, with terephthalic and benzoic acids and TOFA. These are used to cure liquid bisphenol epoxy resin. Properties are listed. Coating compositions containing curing agent are claimed. [322] Starner, W E et al, (Air Products And Chemicals Inc). European Patent 1 024 159 A. Publication Date 02.08.2000. Filing Date 25.01.2000. The curing of epoxy resin contaminated with water has been studied using a commercial curing agent blend, simulating site events for a constructional repair material. This blend comprised poly(oxypropylene)diamine, cyclohexane diamine, adipic acid dihydrazide and phenols, the full composition not being disclosed. This was compared with the use of poly(oxypropylene)diamine alone. BADGE epoxy with water added up to 20% content by weight was cured by both hardeners, NIR being used to follow the reaction and give curing rates. A second order dependence on hardener was found, with an activation energy of 70 kJ/mol. Water was seen to increase the reaction rate, a published curve showing this increasing up to 6% water content at 60EC. A range of mechanical properties were determined (tensile strength, adhesive shear stress, flexural strength) showing improvement using the commercial blend, deterioration for example of tensile strength being 30% compared to 70% and loss of adhesive shear strength being limited to 10%. Impact strength was not affected with the commercial blend. [323] Chen, J et al, J. Appl. Polym. Sci., 10 Jan.2001, vol.79 (2), pp214-220. The effect of three different hardeners used to cure low MW epoxy resin modified with pMMA has been studied. Bisphenol epoxy n = 0.15 was used. PMMA was of Mn 47,000 and a miscibility check showed this to be completely miscible with epoxy resin before curing. Tgs were measured across the full range of blends. Curing was carried out with 4,4'-methylenebis-[3-chloro-2,6diethylaniline] (MCDEA), 4,4'-diaminodiphenyl sulphone (DDS) and 4,4'-dimethylaniline (MDA). It was seen that use of DDS or MDA leads to a 2-phase structure while using MCDEA gives material that is only slightly turbid. In the former cases, DMA and TEM results confirm the 2-phase structure, while for the latter DMA shows a single broad relaxation and microscopy shows no phase contrast. In this case pMMA is probably expulsed by the network on a small scale giving what is termed a semi IPN. The phase separated samples exhibit acceleration of the curing reaction just after phase separation, this being absent with MCDEA cure. DMA, conversion and Tg data is included. [324] Ritzenthaler, S et al, Polymer 2000, vol.41(16), pp.6375-6386. Epoxides : Cationic Curing Studies have been made on epoxy resins that are cured by cationic latent thermal catalysts, including the effect of the catalysts on the thermal, rheological and mechanical properties. N-benzylpyraziniumPage 9

CURING TYPES

hexafluoroantimonate (BPH) and N-benzylquinoxalinium hexafluoroantimonate (BQH) were used (whose synthesis has been described elsewhere), to cure low MW bisphenol epoxy resin, with DSC used to explore cure and thermal properties. Crosslinking activation energies and gel times are listed for temperatures between 110 and 150EC, where BQH had the higher energies. Flexural strength and impact properties with BQH were also superior, resulting from the substituted benzene group of the BQH catalyst which increased the crosslink density and structural stability of the epoxy system; the elastic modulus of this system is lower. NIR was used to investigate the cure reaction (reported in more detail for BPH in the second reference). Gelation was seen to begin with the reaction between epoxide groups or hydroxyl groups with catalyst. Other properties are reported and SEM photographs of fracture surfaces of cured samples are included. [325] Park, S-J et al, J. Polym. Sci., Polym. Chem., 1 Jan.2001, vol.39 (1), pp187-195; J. Polym. Sci., Polym. Phys., 1 Feb.2001, vol.39 (3), pp326-331. An investigation is reported into the thermal stability and toughening of epoxy resin with polysulphone resin. A bisphenol epoxy (BADGE) was used with a commercial polysulphone (PSF) resin used as toughening agent. A latent cationic catalyst N-benzylpyrazinium hexafluoroantimonate (BPH) was used (see item [325]) at 1% level, cure being carried out at 1 hour at 70EC. PSF levels from 0 to 40% by weight were included. Latent properties were studied through measurement of conversion as a function of curing temperature, with the cure activation temperature being studied by the Kissinger method using DSC analysis. BPH was found to be a thermally excellent latent initiator without requiring co-initiator. Cure activation energies increased as PSF content increased. Thermal stability was examined by TGA. There was a marginal decrease in both thermal and mechanical properties in the blend system due to phase separation between epoxy and PSF. Full data and SEM photographs of fracture surfaces are included. [326] Park, S-J.& Kim, H-C, J. Polym. Sci., Polym. Phys., 1 Jan.2001, vol.39 (1), pp121128. Epoxy Modifiers Reactive block copolymers with polyisoprene as one block have been used for modification of thermosetting epoxy composites. Poly(methyl acrylate-co-GMA)-b-polyisoprene copolymers were made by nitroxide mediated free radical polymerisation. Nitroxide and alkoxyamine initiator were used to copolymerise MA/GMA. To this was then added isoprene monomer to prepare copolymer with 67% isoprene. This was blended with bisphenol A based liquid epoxy resin which was cured with 4,4'-methylenedianiline (MDA). SAXS, TEM and DSC were used to examine the product. The reactive copolymer remains well dispersed in the epoxy matrix during cure, with a kinetic retardation of macrophase separation by gelation of the curing thermoset. Indications are that the epoxy groups in the block copolymer covalently link to the epoxy matrix. Thermoset-ordering similar to that observed with pEO based block copolymers were observed. The toughening properties are under examination. SAXS patterns and TEM images are included with the microphase separation processes shown diagramatically. [327] Grubbs, R B et al, Macromol., 26 Dec.2000, vol.33 (26), pp9522-9534.

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Functional Acrylic and Vinyl Polymers Hydroxy functional polystyrenes prepared by anionic polymerisation have been used in an in-situ compatibilisation process with p(butylene terephthalate) (pBT). Samples of pSt were prepared with 1, 2 and 4 phenol end groups using specially synthesised terminating agents for standard lithium initiated anionic pSt polymerisations. The phenol groups on mono and di 4-hydroxybenzophenones were protected by silylating with t-butyldimethylsilylchloride followed by a Wittig reaction to form the appropriate 1,1-bis(4-substituted-phenyl)ethylenes. The processes for making these and of the anionic polymerisations are fully described. The pSt Mns were in the 14 - 22,000 range. Binary blends of a non-functionalised pSt or ternary blends also with one of the functionalised pSt polymers and commercial pBT were prepared in an injection moulder at 250 and 270EC. FTIR, DSC and GPC were used to demonstrate that slow alcoholysis took place linking the functionalised pSt with the pBT. Catalyst and conditions were varied to control pBT degradation. The second paper cited studies catalyst and conditions and the effect on mechanical properties. [328] Su, W-Y et al, Polymer, 16 Mar 2001, vol.42(12), pp. 5107-5120 and 5121-5134. Vinyl polymer may be prepared with terminal functional groups such as hydroxyl, amino, epoxy, carboxylic acid, ester, ether, amide or silyl groups, by the addition of a functional group containing olefin compound of low polymerisability to a living radical polymerisation system during or after polymerisation. An ATRP process is claimed, carried out using metal complex catalyst and a functional group containing organic halide or halogenated sulphonyl compound as an initiator. The body of the patent lists a vast range of possible ways that terminal groups may be achieved through this process. In the examples, all have butyl acrylate polymerised with cuprous bromide and pentamethyl-diethylenetriamine and with either methyl 2-bromopropionate or diethyl 2,5dibromoadipate to achieve one or two terminal functional groups respectively. The final addition in the polymerisation obtains terminal groups as below. Additive Diene e.g. 1,7-Octadiene 4-Pentenol Allyl alcohol 8-Dimethoxymethylsilyl-1-octene Terminal Group Olefinic group OH group Epoxy group Silyl group

bis(acetoxy)-2-butene as chain transfer agent. The catalyst was 1,3-bis(2,4,6trimethylphenyl)imidazol-2-ylidene)(PCp3)(Cl2Ru = CHCHC(CH3)2, where Cp is cyclopentyl. Polymer prepared had acetoxy end groups which became OH after treatment with NaOH. Experiments listed in one series show polymers all with Mn between 1500 and 2600, polydispersities being mainly around 1.4 - 1.5. Reaction temperatures were either 25 or 55EC. In another series, variation of monomer to CTA ratio gave a series with Mn ranging from 1800 up to 30,000. Polydispersities at higher MW were broader, with polymer yields over most of the range 90% or greater. NMR data is included. It is shown that the polymer is exclusively 1,4 pBuDi with a predominantly trans geometry. [330] Bielawski, C W et al, Polymer, 02 Mar 2001, vol.42(11), pp.4939-4946. Hydroxyurethanes A process for preparing hydroxyurethanes is claimed, these being useful for coatings with improved gloss, impact resistance, adhesion and toughness. They are obtained by reacting a cyclic carbonate with a primary amine in the presence of a base whose conjugate acid has a pKa of 11 or more, for example using as catalyst potassium t-butoxide. A table of pKa values for different materials is included. It is noted as an example of use of this chemistry that glycidyl methacrylate may be reacted with carbon dioxide to give a monomer with a cyclic carbonate structure which may be copolymerised into a copolymer and subsequently crosslinked with a diamine. The example simply shows the effectiveness of potassium t-butoxide as a catalyst by showing the progress of the reaction between 4-[(pivaloyloxy) methyl]-1,3-dioxolan-2-one and N-butylamine with and without catalyst, and as followed by NMR. Data for catalyst concentrations between 1 and 10% are included [331] Anderson, A G, (DuPont), PCT WO 98/50345. Publication Date 12.11.1998. Filing Date 06.05.1998. Also European Patent 0 983 231 A. Interpenetrating Networks (IPNs) Interpenetrating network particles and films prepared from silicone modified St/BA copolymer latex have been prepared, and have been evaluated as a paper coating. Latex is prepared from St/BA with octamethylcyclotetrasiloxane (OTS) and triethoxysilane propyl methacrylate included, with the optimum level of OTS found at 3% on total monomers. Sodium lauryl sulphate (SLS) and ethoxylated nonyl phenol (EO10) were used as surfactants with potassium persulphate as initiator. A seed/feed process was employed. The polymer structure was investigated by IR spectroscopy, with the structure below indicated. Spectra are included.

Studies of latex film shows that film swelling with toluene decreases as OTS level rises. Water absorption also decreases. It is concluded that silicone modification of St/BA latex facilitatesPage 12

CURING TYPES

formation of a uniform paper coating, increasing glossiness of the coated paper. Stability as well as toluene and water resistance are improved. [332] Wu, Y et al, J. Applied Polym. Sci., 10 Jan. 2001, vol.79(2), pp.333-336. Novel semi-IPNs have been prepared through the polymerisation and crosslinking of vinyl silane within polyvinyl chloride films. The pVC film was commercial product containing ABS as impact modifier, with modification by (-methacryloxypropyltrimethoxysilane. Different routes were used where the silane monomer was absorbed first at 70EC into the pVC unmodified, and where this was absorbed with free radical initiator at 70-80EC. Hydrolysis, condensation and drying stages followed. AIBN was the free radical initiator and acetic acid the hydrolysis/condensation (HC) promoter for the silane reaction. It was found that a gel consisting of silane alone was formed prior to the HC process indicating the formation of a semi-IPN. The gel content following the HC step far exceeded the silane content indicating the trapping of a substantial amount of pVC by the silane network. The reaction was followed by NMR and FTIR. The conclusion concerning the structure is supported by the homogeneous molecular structure and morphology found in films. SEM micrographs are included. [333] Sluszny, A et al, J. Polym. Sci., Polym. Chem., 1 Jan.2001, vol.39 (1), pp8-22. Isocyanates The mechanism for the curing reaction of model epoxy compounds with monuron has been explored. Monuron is p-chlorophenyl-N,N-dimethylurea and can be regarded as an isocyanate blocked amine. p-Tolylglycidyl ether as the model monoepoxide was synthesised from p-cresol and epichlorohydrin as is described. Possible intermediates were also synthesised. Thermo FTIR, DSC and liquid-solid chromatography were used to investigate the reaction of the monoepoxy with dicyandiamide and possible reaction products and reaction schemes are drawn out. It was found that the latent hardener monuron not only accelerates curing of epoxy with dicyandiamide but can also be used as a curing agent itself. Cure with monuron starts well below the thermal decomposition temperature. The reaction with epoxy liberates isocyanate which consecutively reacts with the aminoalcohol there as an intermediate or it reacts with oligomers resulting from its reaction with further glyclidyl ethers. Urethanes formed do not cyclise directly under elimination of dimethylamine but react with a further molecule of glycidyl ether to form 2-oxazolidone. This releases aminoalcohol or relating oligomer. Polymerisation proceeds as the favoured reaction, due to the catalytic effect of the basic dimethylamino group of the amino-alcohol. [334] Brockmann, H et al, Int. J. Adhesion & Adhesives, 2000, vol.20(4), pp.333-340. Latex Systems Crosslinkable coating systems are claimed comprising blends of co-reactive latexes which are crosslinkable at room temperature and post-crosslinkable by the action of heat. Reactive monomers of various types are described, where one group are masked aldehydes, and another co-reactive group are from the family of ureido monomers. These two structures are typified by those below.

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In the example quoted the monomer of the first type used is N-(2,2-dimethoxy-1-hydroxyethyl) acrylamide, CH2=CH.CO.NH.CHOH.CH(OCH3)2. The second monomer is ethylimidazolidone methacrylate where C=X is C=O, and A is CH2.CH2. Latexes are prepared using emulsified feed with SPS as initiator and sodium ethoxylated fatty acid sulphate and ethoxylated fatty alcohol as surfactants. Other monomers are EA and MMA. Latexes are blended 50/50 and allowed to film form and react at room temperature when the % insolubles found is 86%. After heating at 160EC, the % insolubles has increased to 93%. Mechanical properties of crosslinked films and storage stability are also reported. [335] Verge, C & Betremieux, I, (Elf Atochem SA), US Patent 6,107,391. Publication Date 22.08.2000. Filing Date 24.04.1998. Thermally reversible covalent crosslinking systems have been obtained from polymers prepared by emulsion processes. Four systems were employedFunctional Polymer Chlorofunctional Polymer from Chloromethyl Styrene Amino functional Polymer from DMAEA Amino functional Polymer from 4-Vinyl Pyridine Chlorofunctional Polymer Crosslinker / Second Functional Polymer Ditertiary Amine Dihalide Dihalide Amino functional Polymer

The emulsion polymerisations were conventional with SLS as surfactant and KPS as initiator. MWs were determined and compositions confirmed by NMR. Comonomers were variously BA and St. For crosslinking, dihalides examined were 1,4-dibromobutane, ","-dichloro-p-xylene and ","dibromo-p-xylene. Ditertiary amines were N,N,N,N-1,4-butanediamine, N,N,N,Ntetramethylethylenediamine and 4,4'-trimethylene-dipyridine. When crosslinker was employed, reaction was in dispersion/solution with stirring, polymer then being precipitated and separated. Functional dispersions were mixed, precipitated and crosslinked during drying. Crosslinked polymers were insoluble even when heated because of the equilibrium between quaternisation and dequaternisation. However, when a monofunctional halide compound (benzyl bromide) was added all crosslinked polymers became soluble after heating at 200EC. The dissociation of ionene bridges occurred when polymer was heated to 215E so that polymer could flow under stress, and flowability and thermal reversability of certain of the polymers was investigated. [336] Chen, X & Ruckenstein, E, J. Polym. Sci. Polym. Chem., 15 Dec.2000, vol.38 (24), pp4373-4384.

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CURING TYPES

Oil Based Materials Soybean oil-divinylbenzene (SBO-DVB) thermosetting polymers have been synthesised and their structure and properties examined. Three grades of SBO were used, namely food grade, low saturation grade and a conjugated low conjugated grade. This latter was prepared by treatment with rhodium catalyst producing 100% conjugated product (this is to be reported separately). Boron trifluoride diethyl etherate was used to cationically copolymerise the oil with DVB, starting at room temperature, followed by holding at 60EC and then at 100EC. Catalyst miscibility was a problem, initially solved by the addition of fish oil ethyl ester, where subsequent investigation found that SBO methyl esters were also effective. NMR and DMA analysis show the products to be typical thermosets, with a densely crosslinked polymer network. Moduli are comparable with conventional plastics. Compatability of crosslinked polymer with unreacted SBO was improved with the use of conjugated SBO. Decomposition behaviour has been tested by TGA. Tensile stress-strain behaviour for this system is given in the second reference. [337] Li, F. et al, Polymer, 2001, vol.42 (4), pp1567-1579 and J. Polym. Sci., Polym. Phys., 1 Jan.2001, vol.39 (1), pp60-77. Oxazolines The preparation of self-crosslinkable latex compositions is claimed, which contain oxazoline or oxazine groupings and also contain a water soluble or dispersible acidic resin. Crosslinking is possible at both ambient and at elevated temperatures. The monomer general structure is shown below.

In examples, an acidic acrylic resin such as one comprising AMS/AA/St 34/33/33 with acid number 215 and Tg 95EC is dispersed in aqueous ammonia at 85EC. Into this is then fed over 60 minutes a mixture of MMA/BA and oxazoline monomer using ammonium persulphate as initiator. The monomer used in all examples is 2-(4-ethoxyphenyl)-2-oxazolinyl methacrylate. Particle size around 40 nm is achieved with solids of 43%. In curing examples, butyl cellosolve is added along with levelling aid and compositions are coated onto steel. MEK rub tests show 150 rubs being possible after 1 day and above 250 rubs after 7 days from the best example. Coatings in inks, floorings, paints and overprint varnishes are claimed. [338] Rasoul, H A A & Svoboda, J L, (S C Johnson Commercial Markets), US Patent 6,084,023. Publication Date 04.07.2000. Filing Date 06.10.1999. Heterocyclic-functionalised azo compounds are claimed which are useful as initiators for radical polymerisation of olefinically unsaturated compounds, giving polymers with heterocyclic terminal groups, without side reactions or coupling reactions. In the example, the terminal group featured is 1,3-oxazoline, obtained using 2,2'-azobis[2-(1,3-oxazoline)propane] or 4,4'-azobis-4-cyanopentanoic acid-[5-pentyl-2-(1,3-oxazoline)] ester, prepared as described. The former is from the intermediate 2,2'-azobis[2-methyl-N-(2-chloroethyl)propionamide] prepared as described. The latter is preparedPage 15

CURING TYPES

from the readily available 4,4'-azobis-4-cyanopentanoic acid. The former is shown used in conventional polymerisation of St and of St/ACN, giving polymer with oxazoline termination. Other examples show both initiators used with TEMPO in controlled polymerisation, giving monooxazoline termination. In a further example one of these latter mono-terminated polymers is used to give block copolymer by reaction with monocarboxy-terminated pSt. Preparation is claimed along with use for production of graft and block copolymers (in German). [339] Mulhaupt, R et al, (BASF AG). PCT WO 99/37629. Publication Date 29.07.1999. Filing Date 11.09.1998. Also European Patent 1 049 681 A. Phenolic Resins A C13 NMR study has been carried out on cure acceleration effects with carbonates on phenol formaldehyde resin, with the object of making PF resins more suitable for the manufacture of particle board. The PF resole used in the investigation was synthesised as described from 90% phenol and paraformaldehyde, with NaOH catalyst and produced as a 40% syrup. Propylene carbonate and sodium and potassium carbonates were used as cure accelerators as aqueous solutions, curing after adding these solutions then being carried out at 120EC for 10 minutes. The cure results were examined by both liquid and solid state NMR, using certain model compounds as aids to peak assignment. Details are tabulated. It is concluded that the cure mechanism with propylene carbonate seemed to involve increased reactivity of resole phenol rings leading to increased functionality. The alkaline carbonates in contrast apparently caused ortho-ortho linkages to be formed. Spectra and detailed discussion are included. It was noted that cure accelerated PFs were less rigid than the control PF. [340] Park, B H & Riedl, B, J. Applied Polm. Sci., 2000, vol.77(6), pp.1284-1293. Polyesters : Saturated Esters and polyesters are prepared in high yield with improved esterification rates in a low-cost process from polyol containing secondary hydroxyl groups, using C 1-3 alkyltin catalyst. Polyol (polydiol) compound and polycarboxylic, preferably dicarboxylic, compounds are reacted in the melt phase at 160 - 280EC with solvent present as specified, preferably with dimethyltin oxide catalyst. Examples are for the preparation of TMPD/TMP/IPA/ADA polyester, where comparison is given between the use of dibutyl tin oxide, butylstannoic acid and dimethyl tin oxide. The latter is clearly superior giving fastest conversion times to low AV, times to low AV being 4, 2.5-3 and 2.5 hours respectively. The patent claims list a large number of other methyl-tin compounds as useful. [341] Tanner, J T & Honeycutt, A, (Eastman Chemical Company). PCT WO 99/28368. Publication Date 10.06.1999. Filing Date 03.12.1998. Also European Patent 1 036 105 A Low-solvent or solvent-free, low-emission binder compositions are claimed, useful for coatings and inks. These comprise polyester resins based on hydroxy or amino terminated oligomers derived from the usual polyester ingredients including the polyanhydride of a polycarboxylic acid. Free carboxy groups may be at least partially neutralised with bases. Crosslinker and optionally solvent are included. The preparation of a polyester as claimed is exemplifed by a reaction sequence, where first an oligomeric polyester glycol is prepared by the reaction conventionally of adipic acid, NPG andPage 16

CURING TYPES

hexane diol. Two different polyanhydrides may then be reacted with this oligomer. In one example, this is simply benzophenone tetracarboxylic dianhydride. In the other example, a trimellitic ester dianhydride/anhydride mixture was prepared by adding a hexane diol/EG mixture to TMA at 180EC, and then distilling under vacuum. Methylhexahydrophthalic anhydride was added to the residue. The oligomer/polyanhydride reaction products were blended with MF resin, applied as films and crosslinked by stoving at 160EC for 45 minutes. Coatings and inks are claimed. [342] Blum, R & Chmielewski, D, (PPG Industries Inc). PCT WO 98/46689. Publication Date 22.10.98. Filing Date 09.04.1998. Also European Patent 0 975 702 A. Studies on the synthesis of hydroxyl-terminated isophthalate-based oligoesters via a transesterification reaction have been disclosed. Dimethyl isophthalate (DMI) was transesterified with excess of hexane diol (HD), 2-methyl-1,3-propane diol (MP), NPG and 1,10-decanediol in the presence of for example dibutyl tin dilaurate varying the DMI/diol ratio, the reaction time, the heating procedure and the catalyst type and amount. Some mixed diol experiments were also carried out. The oligoester proposed as useful for high solids paint applications was that prepared by reacting DMI/HD/MP 1/1/5/1.5 molar. A preparation technique was developed so that narrow MW distribution and low viscosity could be achieved. Catalyst selection and heating procedure were found important, it being necessary to keep the reaction temperature below 210EC. This material was found to enhance physical properties in derived coatings. The inclusion of MP was found necessary to prevent crystallisation. It was shown that bulky side groups raise the viscosity in this type of liquid oligoester. [343] Diakoumakos, C D & Jones, F N, Polymer, 2001, vol.42 (6), pp2277-2288. Polyesters : Unsaturated Unsaturated polyesters have been modified with toluene diisocyanate (TDI) and the effect of the concentration used on the properties of unsaturated polyester resins examined. Three commercial polyesters were used, two of high and low viscosity respectively, based on phthalic/maleic anhydrides with mixed ethylene and diethylene glycols. The third was based on these ingredients with additional glycolysed waste PET. Each was treated with TDI at 1, 2 and in some cases 3% TDI, styrene levels also being varied. The resins were cured with MEK peroxide and cobalt octanoate, with post curing after exotherm ceased at 80EC. Exotherm peaks were studied for the different resins when it was seen that TDI modification suppressed the exotherm peaks. Gelation times also increased. Mechanical properties of indentation hardness and Charpy impact were tested along with thermal resistance and initial decomposition temperature (IDT). A principle disadvantage from this modification was the viscosity increase with 2% TDI and above, limiting the practical maximum modification to 1%. [344] Gawdzik, B et al, J. Appl. Polym. Sci., 14 Feb.2001, vol.79 (7), pp1201-1206. The cure kinetics of unsaturated polyester resins has been investigated by DSC and by thermal scanning rheometry (TSR). A commercial propylene glycol maleate phthalate resin with 33% St monomer was used, found by NMR to be PG/MA/PA 1.1/0.5/0.5 molar, with maleate extensively isomerised to fumarate. MEK peroxide was used with cobalt octoate (6% Co) as initiating system, with peroxide used at 0.5, 1 and 1.5% and Co catalyst at 0.3%. Isothermal DSC cure was carried out at temperatures between 30 and 80EC, cured samples being then cooled and residual heat ofPage 17

CURING TYPES

reaction determined by scanning at 10EC/min until no further exotherm was observed. Total heat outputs were the same for all conditions. Reaction order, activation energy and rate constant were calculated. The reaction process was found to be complex, with various peaks shown on traces, and changes in parameters and reaction order with reaction conditions. This is discussed. TSR was used to follow changes in viscoelastic properties up to full conversion. The gel time varied with criteria used. Full data is included. [345] Vilas, J L et al, J. Appl. Polym. Sci., 18 Jan.2001, vol.79 (3), pp447-457. A comparison has been published of the low temperature polymerisation of unsaturated polyester and vinyl ester resins. Those used in this study were a low shrink dicyclopentadiene polyester resin of Mn 508 and a bisphenol A based vinyl ester resin of Mn 970. Both were styrene thinned. Curing was with MEK peroxide and Co octoate at 0.8% and 0.1% as cobalt respectively. DSC was used to study reaction rate, where the effects of temperature, initiator, promoter, benzoquinone (BQ) inhibitor and retarder were all examined. Acetylacetone (2,4-P) was used as the retarder/copromoter. Conversion and reaction rate v time curves are included for all of these variants. Use of BQ was seen to provide a longer induction period and higher final conversion for the polyester as compared to the vinyl resin, and was therefore seen as a better inhibitor for polyester resins. 2,4-P was seen to be a good retarder for vinyl ester resins but was an accelerator for polyesters. A gel time model was also developed for the resins, allowing reasonable prediction for the effects of temperature, inhibitor and retarder. [346] Yang, H & Lee, L J, J. Appl. Polym. Sci., 14 Feb.2001, vol.79 (7), pp1230-1242. Polyurethanes 1,2,4-triazole blocked polyisocyanate crosslinkers are claimed which are useful for powder coatings. These are obtained in solvent-free process by reacting bis(4-isocyanatocyclohexyl) methane derivatives and 1,2,4-triazole under melt reaction conditions (150EC or less), cooling and pulverising. In examples, H12MDI is reacted in various forms with 1,2,4-triazole in the presence of dibutyl tin dilaurate. The H12MDI forms are isocyanurate trimer, and as adducts with diols and polyol such as TMP, 1,6-hexane diol, in some cases, the isocyanurate being blended with the polyol adduct. Polyurethane powder coatings are claimed, with a low cure temperature and improved physical properties. [347] Yonek, K P et al, (Bayer Corporation). European Patent 1 028 135 A. Publication Date 16.08.2000. Filing Date 15.12.1999. New isocyanate-based low-temperature hardeners for powder coatings are discussed which are ketoxime-blocked isocyanates. These are activated by the joint action of heat and UV at 100EC giving amine groups able to react with epoxy groups. Firstly in this investigation, HDI was protected with benzophenone oxime and with acetophenone oxime. The UV spectra of these were determined, and use in crosslinking a GMA containing acrylic copolymer examined. Reaction occurred, but use was marred by limited compatability of the components. Oxime blocking of unsaturated isocyanate copolymers from 2-(isocyanatoethyl) methacrylate (IEM) and from TMI were also examined. Copolymers with IEM containing GMA could also be crosslinked, but again compatability appeared to limit the amount of crosslinking possible. Surprisingly, copolymers of MMA with IEM which was acetophenone oxime blocked crosslinked both thermally and by UVPage 18

CURING TYPES

irradiation without further ingredient addition. The pathways are discussed. For blocked TMI copolymers, reaction required the presence of a reactive epoxy material, the most effective being TGIC. The potential of these materials appears to have been demonstrated. [348] Roescher, A & De Ruiter, B, Proc. XXV FATIPEC Congress, Turin, 19-22 Sept.2000, vol.1, pp175-190. Metal organo complexes, useful for catalysis of isocyanate-hydroxy reaction are claimed. These catalysts are metal diketonates, and are mixtures of tetrakis-(2,4-pentanedionato) zirconium with diketones or alkylacetoacetates. In examples, a range of zirconium compounds are first examined where that including 6-methyl-2,4-heptane-dionate appears most successful. In subsequent examples, zirconium tetra 6-methyl-2,4-heptane-dionate is compared with dibutyl tin dilaurate as a catalyst for the reaction of polyol with both aliphatic and aromatic isocyanates. Cure is more rapid and cured films lack the haze that is apparent with the tin compound. The catalytic effect on degradation is also examined and found to be significantly better than that with dibutyl tin diacetate. The catalysts are not deactivated on exposure of the reaction mixture to normal atmosphere, and do not need excess of free diketone. In use they give systems with improved cure at lower temperatures and reduced water sensitivity. The equivalents with hafnium are described but not included in the claims. Compositions containing the catalyst are claimed. Use is for coatings, foams, adhesives, sealants and RIM applications. [349] Blank, W et al, (King Industries Inc), US Patent 5,846,897. Publication Date 08.12.1998. Filing Date 19.03.1997. Also European Patent 1 021 245 A. Silanes/Siloxanes Room-temperature-curable compositions are claimed, giving sealants with improved residual tack and physical properties. These comprise polyether oligomer with reactive silicon groups, blended with high MW or high-viscosity plasticiser. The reactive silyl containing polyether oligomer is derived from the ring opening addition polymerisation of alkylene oxide, further reacted. In examples, propylene oxide is polymerised using polypropylene glycol as initiator with zinc hexacyanocobaltate-glyme complex as catalyst. The hydroxyl ended polymer is then treated with sodium methoxide and 3-chloro-2-methyl-1-propane to convert terminal OH groups to methallyl groups. After drying and the addition of inhibitor, this is treated with dimethoxymethylsilane and a platinum compound to give polyoxypropylene polymer terminated with reactive silane groups. Platinum divinyldisoloxane complex is seen to be a more effective catalyst than hexachloroplatinic acid solution. Sealant is made up with this polymer, calcium carbonate, titanium dioxide, plasticiser and other additives. Tensile and other properties of cured material are tested. [350] Odaka, H et al, (Kaneka Corporation), European Patent 1 036 807 A. Publication Date 20.09.2000. Filing Date 17.03.2000. Highly crosslinked coatings with good mar resistance and tintability, which are especially useful on plastics are claimed. These are obtained from compositions containing alkine-bridged bis or tris aminosilane and an epoxysilane. One of the example formulations for the former is represented as

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RADIATION CURING

In the example included, 3-glycidoxypropyl trimethoxysilane is hydrolysed with water/HCl over 24 hours, and a separate mix of water and 3-aminopropyl triethoxysilane with water is also made and allowed to stand for 24 hours. The application composition is then prepared by mixing the hydrolysed glycidoxy-silane with diglycidyl ether of CHDM (Heloxy 107), the amino-silane and trichloromethane. To this was then added a fluoroester surfactant solution and ethanol. This mixture after a period of cold storage was coated onto polycarbonate lenses and cured at up to 265EF. Dyeing, adhesion and abrasion tests were performed. It is noted that the alkine bridged bisaminosilane is formed during the curing from the combination of the hydrolysed glycidoxy-silane, the amino-silane and the trichloromethane. Coated substrates are claimed [351] Hage, M L, (Vision-ease Lens Inc), US Patent 6,057,040. Publication Date 02.05.2000. Filing Date 22.01.1998. Also European Patent 1 049 747 A.

3.

RADIATION CURING

Applications Radiation-curable coating compositions are claimed which are especially usefull for automotive refinishing basecoats, filler/surfacers, clearcoats and pigmented topcoats. The coatings comprise polymerisable compounds with double bonds containing reactive functional groups and optionally other compounds, free of double bonds, containing addition or condensation reactive groups. (Meth)acryloyl-functional poly(meth)acrylate, polyurethane, polyester, polyester-urethane or epoxy oligomers or polymers may be used, with reactive diluents. Photoinitiator, and optionally solvents, water, pigments and fillers, and the usual additives are included. The one example uses a urethane acrylate oligomer prepared by the reaction of IPDI isocyanurate, neopentyl glycol and hydroxybutyl acrylate. This is blended with a commercial acrylate and OH functional resin (Jagerlux UV 5154B), photoinitiator and additives (HALS and UV absorber). Use is as a clearcoat, cure being under a UV lamp for 80 seconds at room temperature followed by 10 minutes at 60EC. The compositions give good adhesion and high scratch resistance with good chemical, petrol and solvent resistance. Use is also claimed for producing multi-layer coatings (in German) [352] Turk, G A, (Herberts GmbH & Co KG), PCT WO 99/55785. Publication Date 04.11.1999. Filing Date 22.04.1999. Also European Patent 0 991 727 A Storage-stable radiation-curable powder coating compositions are claimed which are useful on a range of substrates. These contain mono or multi valent carboxylic esters, based on the ",$ ethylenically unsaturated carboxylic acid of a $, (, * or , hydroxyalkylamide containing compound, preferably an unsaturated amido ester. In the first examples, ,-hydroxy-(N-ethyl-2-acryloxy) caproamide is prepared by reacting ,-hydroxy-pentyl oxazoline with methacrylic acid. This is subsequently reacted with diisocyanate alone (HDI) or with hydroxy polyester, N,N,N,Ntetramethyl-1-6-hexane diamine and HDI. Simpler products are prepared with hydroxypolyesteramide based on hexahydrophthalic anhydride and diisopropanolamine which is subsequently reacted with methacrylic acid. In actual coating examples, these have photoinitiatorPage 20

RADIATION CURING

added, and optionally unsaturated polyester to give powder coating compositions. Powder is electrostatically sprayed and after melting at 120EC is cured by exposure to UV. Coated substrates are claimed. [353] van Bentham, R A T et al, (DSM NV), European Patent 0 971 004 A. Publication Date 12.01.2000. Filing Date 06.07.1998. A UV-curable coating composition for cathodic electrodeposition is claimed. The composition comprises a polyfunctional acrylate with acryloyl groups and a cathodic electrocoating resin of MW 2000-30000, with 0.1-10 pts/wt of suitable photopolymerisation initiators absorbing UV radiation of wavelength in the range 300-400 nm. In one example, a DMAEM/HEMA/EHA/BMA/MMA/St 40/100/90/50/145/75 copolymer is prepared in isopropanol, apparently by photoinitiation in the presence of two photoinitiators. This is neutralised with lactic acid, the reaction product of HDI isocyanurate and HEA then being added with further photoinitiator and the blend dispersed/dissolved in water. In another example, the cationic resin component is prepared by the reaction of IPDI with caprolactone extended HEA and N-methyldiethanolamine, giving a PU with tertiary amino groups. This is similarly neutralised with lactic acid, blended with polyacrylate and photoinitiator and dissolved/dispersed in water. These compositions are tested by depositing onto Ni plated ABS, dried at 80EC and irradiated with UV. Test results are given alongside some comparative compositions. The compositions are useful for deposition onto metal-plated substrates such as plastics, giving good adhesion and appearance. [354] Fukuda, M & Shimizu, Y, (Shimizu Co Ltd), European Patent 1 036 829 A. Publication Date 20.09.2000. Filing Date 18.03.1999. Cure Monitoring The use of reactive and non-reactive fluorescent probes for monitoring the photoinitiated polymerisation of dimethacrylates has been reported, with reference to the role of luminophore distribution in heterogeneous environments. Probes were based on 4-(dimethylamino)-4'nitrostilbene and the synthesis of these has been reported elsewhere. Different dimethacrylates were polymerised using Irgacure 907 (2-methyl-1-[4-(methylthio) phenyl]-2-morpholinopropanone-1) recording fluorescence measurements on a spectrofluorimeter at right angles. It is found that reactive probes are significantly more sensitive, in particular at the early stages of polymerisation. The observed difference between reactive and non-reactive probes is explained by assuming that covalent attachment affects the distribution of probe molecules between rigid environments, presumably highly crosslinked gel particles, and mobile monomer rich regions. Enrichment of non reactive probes in mobile environments is expected due to diffusion out of the crosslinked regions. [355] Jager, W F & Norder, B, Macromol., 14 Nov.2000, vol.33 (23), pp8576-8582. New Monomers Polymerisable dicyclic esters, useful as monomers for photosensitive resins and other functional polymers are claimed. These have a polycyclic carbon ring structure comprising two or three nonaromatic carbon rings each with two carbon atoms in common and also having polymerisable unsaturated carboxylic acyloxy groups bonded to a carbon atom at a position between two of the rings They are prepared by reacting an alicyclic alcohol as specified with a polymerisable unsaturatedPage 21

PHYSICAL PROPERTIES AND TEST METHODS

carboxylic acid in the presence of catalyst. In examples, the preparation of the alicyclic alcohols is included, so that diols with decalin, perhydroanthracene and tricyclodecane structures are prepared. That for decalin is prepared by the reaction of cis-decalin in an oxygen atmosphere in the presence of N-hydroxyphthalimide and MoO3. This is then reacted with isopropenyl acrylate in the presence of samarium iodide to produce the 4a,8a-bisacryloyloxy-cis-decalin. There are no examples of the polymerisation of these materials. [356] Ishii, Y & Inoue, K, (Daicel Chemical Industries Ltd). European Patent 1 057 806 A. Publication Date 06.12.2000. Filing Date 15.11.1999. New Photoinitiators Stable photoinitiator compositions with good shelf life are claimed. These comprise compositions giving cations on exposure to radiation such as iodonium borate initiator with a stabilising amino agent, for example a secondary or tertiary amine or HALS, and optionally diluent such as diacetone alcohol or hydroxylated carboxylic acid. The iodonium borate can have the general formula

In the example, tetrakis(pentafluorophenyl) borate tolylcumyliodonium is used, where it is shown that the addition of HALS Tinuvin 292 gives a composition stable by pH measure-ment over periods of time at 70E and 120EF. The latter composition retains a higher pH. The HALS thus retards the gradual acidification of the cationic photoinitiator resulting from spontaneous degradation of the iodonium-borate salt. These compositions are stated to be especially useful with organosiloxane compounds containing vinyl or epoxy groups and also with non-silicone compounds containing epoxy groups. Use is claimed. [357] Kerr, III S R & Beaty, R L, (Rhodia Inc), US Patent 5,973,020. Publication Date 26.10.1999. Filing Date 06.01.1998. Also European Patent 1 045 879 A.

4.

PHYSICAL PROPERTIES AND TEST METHODS

Cure Monitoring Techniques of monitoring polymerisation and curing on-line have been thoroughly reviewed, with applicability to both solid and liquid curing systems, including from an industrial context. Following explanations of off-line, on-line and in-line, the principles of each technique are discussed with a diagram of the apparatus, where sensitivity and limitations are given appropriate mention. The coverage is broad with optical and dielectric spectroscopic methods, ultrasonic methods, particle sizing and reaction calorimetry being covered. Also detailed are densitometry, rheometry, chromatography and pH monitoring. The use of spectroscopic techniques is related to use with a number of specific systems, so that UV is referred to for bis-maleimide resin and NIR and Raman have been used for epoxy curing, both with fibre optic sensing. Specifically noted is the use of fibre optic interferometric ultrasound sensors for monitoring epoxy cure, the equipment and techniquePage 22

PHYSICAL PROPERTIES AND TEST METHODS

being shown diagramatically. Again for epoxy cure, dielectric spectroscopy gets extended coverage with the principles, instrumentation and applications detailed. A list reviewing practical considerations concludes the discussion. The paper includes 109 well chosen references. [358] Hegerth, W-D, Sens. Update, 1999, vol.5, pp.191-242. Cure Studies Studies have been carried out on the curing kinetics and total thermal degradation of thiodiphenol based epoxy copolymer modified with penta-coordinated phosphate as a tribranched junction. Phosphate containing 4,4'-thiodiphenol (TDP) was prepared by reacting TDP with triethylamine and phosphorus oxychloride. The epoxy copolymer was then prepared from the reaction product reacted with BADGE epoxy in 1:3 ratio by the hot melt method. Thermal kinetics of the curing process of the modified epoxy were found to follow first order curing obeying the Kissinger equation in similar manner to bisphenol based epoxy. The modified resin however had improved curing properties in a narrower curing temperature range, where a higher initial curing temperature might indicate better ambient storage stability. Thermal stability showed a high LOI value as found from char yields from TGA measurements, indicating an improvement in flammability. Tests show effects from the phosphate section at higher temperatures. Extended mass fragmentation schemes and data are included. [359] Lin, J-F et al, J. Applied Polym. Sci., 2000, vol.77(4), pp.719-732. A new experimental approach is claimed in studying the relationship between the degree of conversion and stress, with the simultaneous measurement of polymerisation kinetics and stress development in radiation-curing of coatings. A cantilever deflection apparatus is described combined with real time FTIR spectroscopy by a reflectance method. Using this the stress is related to molecular architecture in terms of crosslink density. Polymerising systems were from tripropylene glycol diacrylate, TMP triacrylate and PE tetraacrylate, with Irgacure 369 photoinitiator (2-benzyl-2(dimethylamino)-4'-morpholinobutyrophenone. The sensitivity to stress was found to be extremely high and high quality IR spectra were also obtained. Stress build up commenced only after a certain time had elapsed, related to gel formation. Gelation prediction models were examined with Carothers, extended Flory, and models from percolation theories, various lattice models being included. The percolation model results were not in good agreement with the experimental data. The authors developed their own approach based on the probability of finding a relative concentration of reacted or partially reacted monomers relating the stress and degree of conversion of vinyl groups. [360] Stolov, A A et al, Macromol., 19 Sept.2000, vol.33 (19), pp6970-6976.

PRA PublicationsThe PRA publishes the following regular items World Surface Coatings Abstracts (Monthly) About 10,000 abstracts per annum on all aspects relevant to surface coatings, and selective coverage on topics such as adhesives and inks. Both patent and nonpatent literature are covered. Monthly and annual indexes included. Paint Titles (Weekly) Bibliographic listing of some 250 items each week, including summaries of European and British patents. Coatings COMET, Companies, Markets and Trends (Monthly) A business news digest dedicated to coatings, adhesives, inks and their raw materials worldwide. It contains abstracts, editorial features and cumulated statistics. CORE, Coatings, Regulations and the Environment (Monthly) Legislation from around the world and the literature on hazardous materials, health and safety issues, environmental protection, waste management, transport, etc are presented in predigested form. Waterborne and High Solids Coatings (Monthly) A critical survey of recent publications and patents. News items are included. Emulsion Polymer Technologies (Monthly) Detailed summaries (about 480 per annum) of patents, journal articles etc. Non-coating uses of emulsions are included. European Paint & Resin News (Monthly) A concise summary of all coatings industry news, latest market data and forthcoming events, with the emphasis on Europe where possible. Perfect for keeping up-to-date with industry developments. Radnews (4 issues per annum) A technical bulletin aimed at serving all aspects of the radiation curing industry, from R and D to production and use. Regular features include full length feature articles, literature reviews, European Union regulatory updates and patents abstracts. SHE Alert (Monthly) An alerting service on safety, health and the environment, comprising a digest section, substance monitor (individual chemicals index), occasional features and a regularly updated reference section. Includes legislation and developments relating to topics such as pollution control, chemical hazards, consumer safety and market restrictions.

A publications catalogue listing these and other products is available from the PRA on request.

MEETINGS, CONFERENCES etc

The 7th International Workshop on Polymer Reaction Engineering will be held on 8 - 10 October in Hamburg, Germany. Details including how to register and details of the program can be obtained from http://www.dechema.de/englisch/veransta/pre7.01/ pages/f_pre_1.htm. The main subjects of the workshop include - New polymerization reactor concepts and new polymerization processes - Polymerization in supercritical fluids - Emulsion polymerization/Functionalized polymer particles/Polymeric nano-particles - Computational fluid dynamics (CFD) simulation in polymerization processes - Novel reaction systems - Material properties: Understanding on the molecular level - Polymer properties of functionalized polymers - Microreactors in polymerization technology Keynote lectures will be given by amongst others: M.S. El-Aasser, Lehigh University, Bethlehem. Nano-Polymer Particles: Their Functionalization and Morphology. R.O. Fox, Iowa State University, Ames. CFD in Polymer Reaction Engineering: Combining Polymerization Chemistry and Detailed Flow Models. S.M. Howdle, University of Nottingham. Supercritical Fluids: New Solvents for Polymer Synthesis and Polymer Processing. K. Kremer, MPI fr Polymerforschung, Mainz. Molecular Simulation of Polymers: From Concepts to Industrial Applications. R. Mlhaupt, Albert-Ludwigs-Universitt Freiburg. Combinatorial Chemistry for the Development of New Catalysts and Polymeric Materials: Prospects and Challenges. P. Rosendorfer, Elenac GmbH, Ludwigshafen. LUPOTECH G - Bridging the Gap between High Performance Products and a Low Cost Process. A. de Vries, Montell Italia, Ferrara. The MultiZone Circulating Reactor Technology.

Electronic VersionThe PRA journals

Emulsion Polymer Technologies

and

Polymer Curing Technologies

are now available in electronic format as well as in printed versions.

The data is in Adobe Acrobat format and can be supplied on floppy disc or by electronic mail. In this format, the document can be displayed as though it were a printed document and can be printed out. In addition, a word processor type word search option can be used to take you to the locations at which a word occurs. The Adobe Acrobat Reader required is readily available. The price for the electronic version alone is the same as for the printed version. If you wish to subscribe to both the printed and electronic versions the combined price (before any VAT) is 50 higher than the price for the printed copy alone (see below). The May 2001 to April 2002 prices are therefore Emulsion Polymer Technologies Printed version: Non-members 320 (PRA members 270) Electronic version: Non-members 320 (PRA members 270) * Printed plus electronic versions: Non-members 370 (PRA members 320) * Polymer Curing Technologies Printed version: Non-members 210 (PRA members 180) Electronic version: Non-members 210 (PRA members 180) * Printed plus electronic versions: Non-members 260 (PRA members 230) * * Plus VAT at 17 % on the full figure for 1) any European Union customer without a VAT number 2) all UK customers.